Various approaches have been made in efforts to obtain greater efficiency from the combustion of liquid fuels used in internal combustion engines. More recently, these efforts have also included means to reduce the amount of moxious or toxic exhaust gases.
For example, devices and apparatus have been suggested wherein part or all of the exhaust gases are recirculated to provide the heat to vaporize liquid fuel whereupon the liquid fuel thus vaporized is supplied to the manifold for subsequent combustion. These approaches are illustrated by U.S. Pat. No. 1,950,800 to J. A. Mathes, U.S. Pat. No. 2,749,223 to J. R. Harrington, U.S. Pat. No. 3,273,983 to C. Minoza, U.S. Pat. No. 3,886,919 to A. M. Freeman and U.S. Pat. 3,931,801 to W. J. Rose et al.
In some approaches, the vaporized fuel is passed through a carburetor prior to being supplied to the manifold for combustion such as are disclosed in U.S. Pat. No. 2,272,341 to G.L. Holzapfel and U.S. Pat. No. 2,306,897 to J. Ollig, while other approaches reveal the use of separate heating units to accomplish vaporization such as are disclosed in U.S. Pat. No. 2,853,988 to J. Perepolkin, U.S. Pat. No. 3,380,442 to A. O. Johnson, U.S. Pat. 3,411,489 to J. Kruger and U.S. Pat. No. 3,788,292 to S. Lee, Jr.
All of these approaches require either the use of a constant source supply of heat, or elaborate circulating and feed means for the liquid fuel and heat supply, or the addition of another component such as a heat exchanger to continuously supply heat, or the use of additional, separate elements to accomplish proper mixing of liquid fuel with vaporized fuel.